Injections and poliomyelitis: what are the risks of vaccine associated paralysis?

Provocation by injections can increase the risk of paralytic poliomyelitis by up to 25 fold. In England and Wales the risk of provocation paralysis from DPT given with oral poliovirus is 1 to 2 cases per million children immunized. Cases in India following immunization with oral poliovaccine and DPT are likely to be caused by wild rather than vaccine virus. Most cases of poliomyelitis in the Third World probably follow provocation by unsterile and unnecessary injections. There should normally be very few cases due to immunization. Injections should be sterile and only given when necessary.